import java.util.Stack;
class Solution20 {
    public boolean isValid(String s){
        Stack<Character> stack = new Stack<>();
        for (int i = 0; i <s.length() ; i++) {
            char c = s.charAt(i);
            if(c=='[' || c=='(' || c=='{')
            {
                stack.push(c);
            }else
            {
                if(stack.empty())
                    return false;
                char topChar = stack.pop();
                if(c == ')' && topChar !='(')
                    return false;
                if(c == ']' && topChar !='[')
                    return false;
                if(c == '}' && topChar !='{')
                    return false;
            }
        }
        if(stack.empty())
            return true;
        else
            return false;
    }

    public static void main(String[] args)
    {
        Solution20 s = new Solution20();
        System.out.println(s.isValid("[](){}"));
    }
}
